CheckObjCInstMethSignature.cpp revision 7dd445ec20e704846cfbdb132e56539280d71311 
1//=- CheckObjCInstMethodRetTy.cpp - Check ObjC method signatures -*- C++ -*-==//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file defines a CheckObjCInstMethSignature, a flow-insenstive check
11//  that determines if an Objective-C class interface incorrectly redefines
12//  the method signature in a subclass.
13//
14//===----------------------------------------------------------------------===//
15
16#include "ClangSACheckers.h"
17#include "clang/StaticAnalyzer/Core/CheckerV2.h"
18#include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
19#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
20#include "clang/AST/DeclObjC.h"
21#include "clang/AST/Type.h"
22#include "clang/AST/ASTContext.h"
23
24#include "llvm/ADT/DenseMap.h"
25#include "llvm/Support/raw_ostream.h"
26
27using namespace clang;
28using namespace ento;
29
30static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
31                               ASTContext& C) {
32
33  // Right now don't compare the compatibility of pointers.  That involves
34  // looking at subtyping relationships.  FIXME: Future patch.
35  if (Derived->isAnyPointerType() &&  Ancestor->isAnyPointerType())
36    return true;
37
38  return C.typesAreCompatible(Derived, Ancestor);
39}
40
41static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
42                               const ObjCMethodDecl *MethAncestor,
43                               BugReporter &BR, ASTContext &Ctx,
44                               const ObjCImplementationDecl *ID) {
45
46  QualType ResDerived  = MethDerived->getResultType();
47  QualType ResAncestor = MethAncestor->getResultType();
48
49  if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
50    std::string sbuf;
51    llvm::raw_string_ostream os(sbuf);
52
53    os << "The Objective-C class '"
54       << MethDerived->getClassInterface()
55       << "', which is derived from class '"
56       << MethAncestor->getClassInterface()
57       << "', defines the instance method '"
58       << MethDerived->getSelector().getAsString()
59       << "' whose return type is '"
60       << ResDerived.getAsString()
61       << "'.  A method with the same name (same selector) is also defined in "
62          "class '"
63       << MethAncestor->getClassInterface()
64       << "' and has a return type of '"
65       << ResAncestor.getAsString()
66       << "'.  These two types are incompatible, and may result in undefined "
67          "behavior for clients of these classes.";
68
69    BR.EmitBasicReport("Incompatible instance method return type",
70                       os.str(), MethDerived->getLocStart());
71  }
72}
73
74static void CheckObjCInstMethSignature(const ObjCImplementationDecl* ID,
75                                       BugReporter& BR) {
76
77  const ObjCInterfaceDecl* D = ID->getClassInterface();
78  const ObjCInterfaceDecl* C = D->getSuperClass();
79
80  if (!C)
81    return;
82
83  ASTContext& Ctx = BR.getContext();
84
85  // Build a DenseMap of the methods for quick querying.
86  typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
87  MapTy IMeths;
88  unsigned NumMethods = 0;
89
90  for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
91       E=ID->instmeth_end(); I!=E; ++I) {
92
93    ObjCMethodDecl* M = *I;
94    IMeths[M->getSelector()] = M;
95    ++NumMethods;
96  }
97
98  // Now recurse the class hierarchy chain looking for methods with the
99  // same signatures.
100  while (C && NumMethods) {
101    for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
102         E=C->instmeth_end(); I!=E; ++I) {
103
104      ObjCMethodDecl* M = *I;
105      Selector S = M->getSelector();
106
107      MapTy::iterator MI = IMeths.find(S);
108
109      if (MI == IMeths.end() || MI->second == 0)
110        continue;
111
112      --NumMethods;
113      ObjCMethodDecl* MethDerived = MI->second;
114      MI->second = 0;
115
116      CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
117    }
118
119    C = C->getSuperClass();
120  }
121}
122
123//===----------------------------------------------------------------------===//
124// ObjCMethSigsChecker
125//===----------------------------------------------------------------------===//
126
127namespace {
128class ObjCMethSigsChecker : public CheckerV2<
129                                      check::ASTDecl<ObjCImplementationDecl> > {
130public:
131  void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
132                    BugReporter &BR) const {
133    CheckObjCInstMethSignature(D, BR);
134  }
135};
136}
137
138void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
139  mgr.registerChecker<ObjCMethSigsChecker>();
140}
141